Improvement in the construction of iron truss-bridges



C. KELLGG.. Construction of Irun Truss-Bridge.

N.o'.l62,077'.

PafenredApri|13,1875.

7795i@ rfa-def,

rE STATES PATENT FFIC.

CHARLES KELLOGG, OF ATHENS, PENNSYLVANIA.

IMPROVEMENT IN THE CONSTRUCTION OF IRON TRUSS-BRIDGES.

Specification forming part of Letters Patent No. 162,077, dated April 13, 1575; application tiled December 3, 1874.

To all 'whom it may concern Be it known that I, CHARLES KELLOGG, of Athens, Bradford county, Pennsylvania, have invented certain Improvements in the Construction of Bridges, of which the following is a specication My invention relates to the mode ot' constructing and retaining in their places the pins used in the construction of truss-frame bridges, such, for instance, as the pins for connecting the posts, lower chord-rods, and diagonals together; and the object of my invention is to obviate the difliculties experienced in the use of ordinary pins ot' this class.

Before I proceed to describe my invention it will be well to refer to the usual bridgepins, one ot' which is illustrated in Fig. l ot' the accompanying drawing. It consists of a solid cylinder ot wrought iron, threaded at each end for the reception of a nut, a, by which nut the pin is retained in its place. The diflculty with these ordinary pins is that in driving them into their places, and even during transportation,the screw-threads are apt to become so wounded that it is a difficult matter to apply the nuts. This dii'culty has been, in a measure, overcome by reducing the ends ot the pins in diameter where they receive the nuts, and by screwing a tapering cap, d, on one end ot' the pill to facilitate driving, and to protect the screw-thread. the cap being removed to make way for a nut when the pin has been driven to its place. I obviate these difficulties by constructing the pin, and combining it with retaining-washers in the manner illustrated in Fig. 25, in which A represents the pin, the latter beingmade tapering at each end, so as to facilitate driving. B B are the two outer rods ofthe lower chord, all the chordrods having the usual eyes, through which the pin is driven. To the same pin are connected the post diagonals and counter diagonals, these members lilling the space between the two sets of chord-rods. Over each tapering end of the pin is placed a cup-shaped cast-iron washer, D, which is caused to bear against the eye of the outer chord-rod B by a set-screw, H, adapted to a threaded orice in the end ot' the pin, the washers with their set-screws thus serving to retain the pin in place, and at the same time presenting a neat appearance at the junction of the different members of the bridge.

Owing to the tapering ends of the pins, and to the absence of external screw-threads, they cannot be damaged during transportation, or during the. erection of the bridge, and they can be easily passed through those members which are united at one pin-joint.

As there is always a space between the end of the pin and the washer, the latter can be screwed up so as to press the bars closely together and exclude water from the joint, a result which, owing to the varying thicknesses of the bars, could not always be attained when the ordinary pins were used.

I claim as my invention- The combination ot' the within-described bridge-pin A and its tapering ends with the retaining-washers D and set-screws H.

In testimony whereot'l have signed my name to this specification in the presence of two subscribing witnesses. y

CHARLES KELLOGG.

Witnesses:

F. R. PIKE, D. K. J AOKMAN, Jr. 

